1. Field of the Invention
The invention is related to the field of mechanical couplings which connect one rotatable shaft to another, and more particularly to flexible diaprahgm couplings for interconnecting rotating shafts which may become misaligned with respect to each other.
2. Prior Art
Flexible mechanical couplings have found wide acceptance in industry for the transmission of rotary energy from one device to another. Often it is extremely difficult to mount or install two devices, such as a turbine and an electrical generator, or a motor and a pump so that their output and input shafts are in exact alignment. Even where such alignment may be achieved in the first instance, settling of foundations, shifting of supporting members, or even bearing wear may subsequently cause a misalignment between the two shafts. The resulting misalignment may be an angular displacement, a physical displacement along the axes of the rotary shafts, a physical displacement normal to the shift axes, or a combination of two or more of the above.
To compensate for misalignment between the driving and driven members a variety of flexible couplings have been developed. One form of such flexible couplings is the drive shaft used on present day automotive vehicles. These drive shafts have a pair of universal joints connected to the opposite ends of an extentable shaft. Other examples of flexible couplings are disclosed by Cull in U.S. Pat. No. 3,012,421, Tobin in U.S. Pat. No. 3,800,557, Oyama et al in U.S. Pat. No. 3,905,208 and Gebauer et al in U.S. Pat. No. 4,092,837. Cull teaches a rubber insert bonded between a splined or convoluted metal hub and a convoluted exterior. Tobin teaches a universal joint having a laminated rubber coupling. Oyama et al, like Cull teaches a rubber insert bonded between metallic cylindrical members while Gebauer et al teaches rubber isolation members between parallel plates. In addition to couplings having universal joints and rubber inserts, flexible couplings having flexible metal diaphragms interconnected between the driving and driven members have been developed. The flexible diaphragm couplings avoid the maintenance and breakdown problems associated with universal joints and rubber inserts making them more reliable. Further these couplings are capable of transmitting higher torques than is possible with couplings having universal joints or using rubber inserts.
These flexible diaphragm type couplings may include one or more flexible metal diaphragms as disclosed in U.S. Pat. Nos. 4,133,187 and 3,808,837. The flexible diaphragms may be bolted or welded to the interconnecting shaft as is known in the art and may include a splined coupling between the flexible diaphragm and the shaft to assure the transfer rotary motion without slippage or backlash. As disclosed by Wildhaber in U.S. Pat. No. 4,133,187 the central bore of the flexible diaphragm has a female spline which mates with a male spline formed at the end of the interconnecting shaft. Axial movement of the flexible diaphragm along the shaft is inhibited by a pair of retainer ring welded to the splined shaft, one on either side of the flexible diaphragm. Alternatively, Anderson et al in U.S. Pat. No. 3,808,837 disclose a plurality of flexible diaphragms, each having a splined bore mating with the spline on the connecting shaft which are axially entrapped at the end of the interconnecting shaft between a formed shoulder and an end plate bolted to the end of the connecting shaft. Other patents of interest which disclose splined couplings between the flexible metal diaphragms and the interconnect shaft are Cartwright, U.S. Pat. No. 4,133,188, and Weldhaber U.S. Pat. No. 4,044,571.
Bendall in U.S. Pat. No. 3,759,063 teaches a coupling made from metal or equivalent heat resistant material. Bendall's coupling incorporates two laminated flexible assemblies joined to a serrated shaft at a central location. Axial movement of the laminated assemblies at their junction with the serrated shaft is inhibited by retainer rings seated in grooves machined about the shaft's external surface.
Disclosed herein is a flexible diaphragm coupling having molded plastic components. The disclosed coupling has all the advantages of the diaphragm couplings of the prior art, is of simpler construction, and significantly less costly to make.